Method of joining continuous strands

ABSTRACT

The present invention is directed to a method of forming a joint between end portions of two continuous strands, for example, synthetic filament yarns, that are arranged in overlapping engagement by bonding the end portions together with an adhesive material and shrinking a sheath that is formed solely by wrapping a tie-yarn of heat shrinkable material around the ends of the two strands.

United States atent Wra Se t. 9 1975 [54] METHOD OF JOINING CONTINUOUS 2,808,356 /1957 Kimball 57/142 2,953,418 9/1960 Runton et al. 156/85 2,974,559 3/1961 Coggi 156/84 Inventor: Raymond Patrick y, mg 3,012,398 12 1961 Merkle 57 159 England 3,070,947 1/1963 De Toledo ct al 57/159 3,198,059 8/1965 Phaneuf et al 264/1 [73] Ass1gnee: Imperial Chemical Industries 3400481 9/1968, Christenson 56/86 Llmlted, London, England 3,466,210 9/1969 Wareham .1 156/86 3,526,085 9/1970 111man..... 57/159 1221 1972 3,634,972 1/1972 Illmanu... 57/142 [21] App]. No.: 300,874 3,674,581 7/1972 Kalnin ct al. 156/85 Related US. Application Data [63] Continuation-impart of Ser. No. 54,646, July 13, Primary Examiner-Charles E. Van Horn 1970, abandoned. Assistant ExaminerFrank Frisenda 1,, Attorney, Agent, or FirmCushman, Darby & Foreign Application iriority Data Cu hman July 16. 1969 United Kingdom 35772/69 Feb. 20, 1970 United Kingdom..,. 8225/70 Mar. 12. 1970 Unlted Kmgdom 11930/70 [5,7] ST CT 52 U. C1. 156 5' 57 142' 7 159' 1 S 156/15? The present invention 1s dlrected to a method of form [51] Int Cl 2 D02G3/22 B65H 69/06 ing a joint between end portions of two continuous [58] Fie'ld "156/84 294 296 strands, for example, synthetic filament yarns, that are 156/180 303 1 304 172 arranged in overlapping engagement by bonding the 169 5 5 57/142 end portions together with an adhesive material and G 64030 5, f shrinking a sheath that is formed solely by wrapping a 1 l7'4/D[G tie-yarn of heat shrinkable material around the ends of i the two strands.

{56] References Cited UNITED STATES PATENTS 12 Claims, 2 Drawing Figures 2,577,466 12/1951 Jones 156/86 METHOD OF JOINING CONTINUOUS STRANDS CROSS REFERENCE TO RELATED APPLICATION The instant application is a continuation-in-part of US. application Ser. No. 54,646, filed July 13, I970.

The present invention relates to a method of forming a joint between the end portions of two continuous strands arranged in overlapping engagement.

By the expression two continuous strands" is meant two continuous filaments or two continuous filament yarns.

By overlapping engagement is meant that the end portions of the strands are arranged in side-by-side overlapping relationship and, if desired, have a low level of twist imparted thereto. In the case when the strands are composed of continuous filament yarns, the filaments at an end portion of each yarn may be intermingled together to provide overlapping engagement."

In the majority of textile processing operations it is necessary at some stage to join the end of one strand on a bobbin with the end of another strand on another bobbin in order to maintain a continuous supply of the strand. Knotting of the strands is well known but is not particularly attractive, especially when heavier denier strands are being joined because of the known low efficiency and bulkiness of the knots.

In the method according to the present invention an object is to form a joint between end portions of two continuous strands arranged in overlapping engagement by bonding the end portions together with an adhesive and shrinking a sheath formed by wrapping a tieyarn of heat shrinkable material around the bonded end portions. An advantage for a sheath formed exclusivcly by wrapping is that a less bulky joint is produced which, as aforenoted, is more attractive.

The method is preferably carried out according to the invention by bringing an end portion of one strand into overlapping engagement with an end portion of the other strand, coating the engaging end portions with a solution of a polymeric adhesive, capable of adhering to the strands, in a solvent therefor which is not a solvent for the material of the strands, removing the solvent from the polymeric adhesive to form a bond between the engaging end portions of the strands, covering the bonded end portions by wrapping a heatshrinkable tie-yarn around the bonded end portions to thereby form a spiral sheath, and thereafter shrinking the sheath. Alternatively, the solvent for the adhesive can be removed after the wrapping of the shrinkable tic-yarn sheath, as by heating, so that shrinkage of the sheath occurs simultaneously with solvent removal.

Other objects, advantages, and novel features of the invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. I is a perspective exploded view illustrating a joint being formed by the method of the present invention; and

FIG. 2 is a perspective view showing the finished joint.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS in the drawings two strands to be joined are illustrated at l and la in overlapping relationship with their overlapped portions coated with adhesive. Each strand may be a continuous monofilament having a denier in the range 100 to 1,500, or may be a yarn composed of such monofilaments. Alternatively, the strands may be formed of yarns composed of lower denier filaments, for example, each yarn may have a yarn denier of 1,000 and a denier per filament of 10.

The strands may be composed of filaments which are synthetic or man-made. The strands may be composed, for example, of a polyester or a polyamide, particular examples being poly( ethylene terephthalate) and poly( hexamethylene adiparnide) or the strands may be composed of glass.

The level of twist which may, if desired, be imparted to the engaging end portions of the strands need only be low, of the order of 0.5 to 2 turns per inch.

A sheath 3 is formed in situ about the overlapped bonded ends of the strands 1,141 by tightly wrapping a shrinkable tie-yarn 4 in spiral form, as indicated by the arrow in FIG. I, around the overlapped portions of the strands, with the ends of the tie-yarn 4 being securely fastened to the overlapped strand portion. The tie-yarn 4 may be a single shrinkable monofilament or a low denier multifilament yarn, nylon or polyester being suitable. Apparatus which may be used for wrapping the tie-yarn is described in UK. Patent Application No. l0432/70. The tie-yarn 4 is then subjected to a shrinkage treatment, for example, a heat treatment, which causes the sheath 3 formed by the tie-yarn 4 to tightly hold and grip the bonded, engaged end portions of the strands 1,111.

It will be understood from the above that the wrapping of the tic-yarn 4 is carried out in situ at the overlapped strand portions by imparting progressive spiral movement to the tie-yarn. The operation therefore does not include preforming a sheath and then sliding the sheath longitudinally over the overlapped strand portions.

The molecular weight of the polymeric adhesive is chosen so that it forms tough films and yet does not yield solutions which are too viscous to apply to the ends of the strands to be joined. Preferably, the Intrinsic Viseosity of the adhesive polymer in a solvent therefor is between 0.4 and 0.8 measured at a temperature 0f 25C. Furthermore, the adhesive polymer should not crystallise on heating.

The solvent for the adhesive polymer is preferably removed by the application of a stream of heated air to the area of the engaging end portions of the strands. For this purpose, the solvent should be sufficiently volatile to be readily evaporated at a temperature between C. to 230C. Desirably, the solvent should form free flowing homogeneous solutions of the adhesive polymer at 10% to 30% concentration.

The method of the invention is particularly applicable to the joining together of heavy denier strands which are ultimately to be used as reinforced materials in pneumatic tires for motor vehicles. For this particular application it has been found that the strength of the jointed strands should be at least 60%, and preferably at least 80%, of the strength of each strand. Also, the jointed strands should be capable of withstanding a stretch of at least 1% at a temperature of 200C. to 240C.

Typical conditions which have been found to enable such requirements to be achieved are:

a. The end portions of the strands should be in overlapping engagement of a length of at least 1.25 inches.

b. An application of the adhesive solution sufficient to cover the whole of the surface area of the joint.

0. A heat treatment is used to set the joint, i.e.. to remove the solvent and shrink the sheath. Conveniently. hot air is used for this purpose which preferably has a temperature in the range 180C. to 230C.

:1. The denier of the tie-thread should be about 500 denier. Conveniently, this is a 500 denier monofilament.

0. The shrinkage (at 150C. in air) of the tie-yarn should be greater than 6% and preferably greater than 10%.

f. The tension under which the tie-yarn is wound around the end portions of the strands to form a sheath should be above 50 grams. and preferably should be of the order of 200 grams.

For strands composed of poly(ethylene terephthalate) or glass, at suitable adhesive is a solution in chloroform of an ethylene terephthalate/sebacate eopolyester having 50 to 80 mole 71 of ethylene tercphthalate in the polymer. A particularly suitable adhesive is a solution of 40/60 moles /1 ethylene isophthalate/tcrephthalate copolymer of Intrinsic Viscosity 0.67 in chloroform at C.

It will of course be understood that various changes may be made in the form, details, arrangement and pro portions of the components without departing from the scope of the invention.

What is claimed as novel and unobvious and desired to be protected by Letters Patent is set forth in the appended claims.

What is claimed is:

1. A method of forming a joint between the end portions of two continuous strands comprising the steps of: arranging the end portions in overlapping engagement. applying an adhesive only to the end portions to bond the end portions together. wrapping a heat-shrinkable tie-yarn in spiral form around the bonded end portions and shrinking the wrapped tie-yarn around the bonded end portions.

2. A method of forming a joint as claimed in claim 1, including bringing an end portion of one strand into overlapping engagement with an end portion of the other strand, coating the engaging end portions with a solution of a polymeric adhesive, capable of adhering to the strands, in a solvent therefor which is not a solvent for the material of the strands. removing the solvent from the polymeric adhesive to form a bond between the engaging end portions of the strands, and then carrying out the wrapping and shrinking steps.

3. A method of forming ajoint as claimed in claim 1, including bringing an end portion of one strand into overlapping engagement with an end portion of the other strand, coating the engaging end portions with a solution of a polymeric adhesive. capable of adhering to the strands, in a solvent therefor which is not a solvent for the material of the strands, carrying out the wrapping step, removing the solvent from the polymeric adhesive to form a bond between the engaging end portions and simultaneously shrinking the wrapped tie-yarn.

4. A method of forming a joint as claimed in claim 1 wherein a heat treatment is used to remove the solvent and shrink the tie-yarn.

5. A method of forming a joint as claimed in claim 4 wherein the heat treatment utilises a stream of hot air at a temperature in the range C. to 230C.

6. A method of forming a joint as claimed in claim 1 wherein the tieyarn is a shrinkable monofilament.

7. A method of forming a joint as claimed in claim 1 wherein the tie-yarn has a shrinkage greater than 6%, in air at 150C.

8. A method of forming ajoint as claimed in claim 1 wherein each strand is composed of a single monofilament having a denier in the range to 1.500.

9. A method of making a joint as claimed in claim 1 wherein the strands are formed of glass.

10. A method as in claim 1 wherein the tie-yarn is a low denier multifilament yarn.

11!. A method as in claim 1 wherein each strand is composed of a yarn made from monofilaments having a denier in the range 100 to 500.

12. A method as in claim 1 wherein the strands are formed ofa material selected from the group consisting of polyester and polyamide. 

1. A METHOD OF FORMING A JOINT BETWEEN THE END PORTIONS OF TWO CONTINUOUS STRANDS COMPRISING THE STEPS OF ARRANGING THE END PORTIONS IN OVERLAPPING ENGAGEMENT, APPLYING AN ADHESIVE ONLY TO THE END PORTIONS TO BOND THE END PORTIONS TOGETHER, WRAPPING A HEAT-SHRINKABLE TIE-YARN IN SPIRAL FORM AROUND THE BONDED END PORTIONS AND SHRINKING THE WRAPPED TIE-YARN AROUND THE BONDED END PORTIONS.
 2. A method of forming a joint as claimed in claim 1, including bringing an end portion of one strand into overlapping engagement with an end portion of the other strand, coating the engaging end portions with a solution of a polymeric adhesive, capable of adhering to the strands, in a solvent therefor which is not a solvent for the material of the strands, removing the solvent from the polymeric adhesive to form a bond between the engaging end portions of the strands, and then carrying out the wrapping and shrinking steps.
 3. A method of forming a joint as claimed in claim 1, including bringing an end portion of one strand into overlapping engagement with an end portion of the other strand, coating the engaging end portions with a solution of a polymeric adhesive, capable of adhering to the strands, in a solvent therefor which is not a solvent for the material of the strands, carrying out the wrapping step, removing the solvent from the polymeric adhesive to form a bond between the engaging end portions and simultaneously shrinking the wrapped tie-yarn.
 4. A method of forming a joint as claimed in claim 1 wherein a heat treatment is used to remove the solvent and shrink the tie-yarn.
 5. A method of forming a joint as claimed in claim 4 wherein the heat treatment utilises a stream of hot air at a temperature in the range 80*C. to 230*C.
 6. A method of forming a joint as claimed in claim 1 wherein the tie-yarn is a shrinkable monofilament.
 7. A method of forming a joint as claimed in claim 1 wherein the tie-yarn has a shrinkage greater than 6%, in air at 150*C.
 8. A method of forming a joint as claimed in claim 1 wherein each strand is composeD of a single monofilament having a denier in the range 100 to 1,500.
 9. A method of making a joint as claimed in claim 1 wherein the strands are formed of glass.
 10. A method as in claim 1 wherein the tie-yarn is a low denier multifilament yarn.
 11. A method as in claim 1 wherein each strand is composed of a yarn made from monofilaments having a denier in the range 100 to
 500. 12. A method as in claim 1 wherein the strands are formed of a material selected from the group consisting of polyester and polyamide. 